The purpose of this project is to provide new methods and techniques of experimentation and to collect data relating to the motions and forces generated during mastication. To obtain quantitative information concerning the distribution of chewing pressures at various segments of the dentition, photoelastic stress analysis will be conducted on dental arch segments mounted in a device capable of simulating masticatory motions. The muscles of mastication will be presented by individually activated hydraulic or pneumatic pistons. When the analog mandible is approximated to the model maxilla the forces generated by occlusion will be recorded at intervals along the dental root surfaces through a reflecting polariscope. Determinations of tensile, compressive and torsional forces, when given widely variable oro-facial and occlusal conditions, for each tooth in the test series will be made by means of optical compensation techniques. With the information gained from this study more objective data concerning the interrelationships between form and function in the human masticatory system will be offered.